Hi Francesca,
There is a flaw in this Add in when converting from Easting (X) and Northing (Y) coordinates into GB Grid. What happens is if the coordinate ends in a 6 or higher number it will round up. So, for example, 433266 182577 becomes SU 3327 8258, rather than SU 3326 8257 which it should be. I have corrected this small error in the code and it now works correctly, merely removing the last figures as required.
I have uploaded an edited version of the Spatial.xla along with some instructions and examples of its use. The zip file also includes how to use it in Access.
The new edited version also allows for the creation of 2, 4, 6, 8 and 10 figure grid references from x and y coordinates. They are named accordingly when you go insert the function (e.g. GB_ENtoGrid8fig).
Hope this helps anyone needing to do this function. I have found it invaluable. Thanks Steve and Andy.
Brian
Brian Miller
(Conservation Officer (Buckinghamshire), BBOWT)